Thanks guys, very interesting.
The airport is about 30mins drive from Andorra's main town versus I think 2 1/2 hours drive to Lleida so I would have thought it would have people clambering to get involved (I read that Andorra gets 10 million visitors per year).
Maybe the unsettled weather conditions make it too unreliable and so uneconomical for tour operators / budget airlines?
Pirineus - La Seu d'Urgell Airport | Aeroports de Catalunya - I looked on the "operators" tab but it doesn't seem to link to a page
http://www.laseuairport.com/airportfees.pdf - looks to be massively subsidised?
MrS